A 4G cellular communication system which is currently being discussed is designed based on one basic frame and is designed to provide optimized performance to a user who moves at a low speed. Such a system is designed to support a user who moves at a speed of 350 km/h, but the performance thereof is inferior to that of a user who moves at a low speed. If such a cellular communication system is applied to a high-speed train, link quality between a network and the high-speed train is deteriorated and sufficient link capacity cannot be ensured due to high mobility of 350 km/h. If the speed of the high-speed train will exceed 500 km/h in the future due to technological development, performance deterioration will become more serious and quality of a wireless data service provided to a passenger will be significantly decreased. If a scenario in which a high-speed train uses some capacity of a macro base station (BS) is used, data communication of other users in a cell may be deteriorated.
Accordingly, instead of wireless communication, wired communication may be used for communication between a network and a high-speed train. For example, communication between a high-speed train and a network may be performed through an AC signal using a railroad, with which the high-speed train is in contact. However, in such a system, capacity of the railroad is low and it is difficult to establish more links due to physical restriction that the number of simultaneously connected railroads is restricted to two. Similarly, a power line communication (PLC) method of performing communication using a power line may be used. However, this method has the same disadvantages as the communication method using the railroad and cannot be disadvantageously applied to a train without a power line.
In the present invention, a transmission/reception antenna structure for providing high-speed data communication in such a communication environment is proposed and a method of improving a multi-antenna scheme in a conventional LTE/LTE-A or IEEE 802.16m system so as to minimize pilot overhead and ensure more data capacity is proposed.